Process for improving the quality of lubricating oils



Dec. 23, 1958 R. c. HALTER ETAL 2,865,839

PROCESS FOR IMPROVING THE QUALITY OF LUBRICATING OILS Filed June 19, 1956 2 Sheets-Sheet 2 YIELD ADVANTAGE F01? HYDROF/N/NG FAA/HANDLE LIGHT MOTUR 0/L 0/5 T/LLA TE PRIOR TO PHENOL EX TRACT/0N SEVERLY HYDROF/IVED FRACT/ON M/LDLY HYDROF/NED FRACT/UN FRACTION NOT HYDHOF/fi/ED 75 V0/. Phenol Treat INVENTORS. R/'chard C. Hal/er,

James R. Mil/er,

A r romvg Y.

Utllt PROCESS FOR IMPROVING THE QUALITY OF LUBRICATING OILS Application June 19, 1956,.Serial No. 592,275

8 Claims. (Cl. 208-96) This application is directed to a method for producing improved quality lubricating oils.

This application is a continuation-in-part of U. S. application Serial No. 408,878 for Richard 'C. Halter and James R. Miller, filed February 8, 1954, and entitled Production of Improved Quality Lubricating Oils.

In accordance with the present invention a lubricating oil distillate fraction is treated in a process in which the fraction is hydrogenated under mild conditions of hydrofining by passing it over a cobalt molybdate hydrogenation catalyst in the presence of hydrogen at a temperature within the range of 575 to 750 F. and the reacted product from this hydrofining reaction is separated from gas and at least a substantial portion thereof contacted with a selective'solvent in a-solvent extraction zone to form an extract phase-and a raffinate phase,

crude oils and Coastal type crude-oils see Character-*- istics 'of Crude Oils Currently Produced in.the"United States, by Harold M. Smith, The Oil and Gas Journal,

March 29, 1951, pages 308, 309, 310, 313, 315, 317 and 318. It is not known exactly why the procedure of the present invention results in substantially improved results particularly when applied to lubricating oil distillate fractions derived from Mid-Continent type crudes and Coastal type crudes. By way of explanation, it is postulated that these distillate lubricating oil fractions contain a non-aromatic fraction of relatively low viscosity index and relatively high 'bromine number which cannot be removed economically by solvent extraction. It is further postulated that in the process of the present invention the hydrofining step converts said fraction to form which either is :a morerdesirable lubricating oil component or a form which may be removed more readily by solvent 'extraction of both?" However, this" is given'only by'way of possible explanation of the improved resultsobtained in the practice'of the present invention and is not presentedby way of limitation.

The practice of the=presentc invention .will now be describedfin greater detail in conjunction with the. draw-,

ing in which:

treating a lubricating oil fraction derived from a Coastal type crudetwhile Fig.- 2 is in the form of a -diagrammaticiiovv- --sheet--- 7 illustrating the practice of the present invention when treating a lubricating oil derived from a Mid-Continent.

type crude oil; and

Fig. 3 is in the form of a series ofcurves-illustratirig .i the improved results obtained in the practice of the present invention.

16 into which it is discharged from line 14.."

The hydrogen added to the lubricating oil fraction" through line 15 is in an amount within the range of" of hydrogen per barrel 200 to 2000 standard cubic feet of said oil distillate.

Reaction zone 16 contains a hydrogenation catalyst; A suitable catalyst may consist of cobalt molybdate within the range of 5% to 25% by weight and silicafree alumina in an amount Within the range of'95% Yto. As .a specific example, the cobalt by weight. molybdate hydrogenation catalyst'may have a composition which is 15% by weight of cobalt molybdateandi" Other suitable hydrogena tion catalysts for this process. include! molybdena on alumina, such as 8 to 10% M003 on alumina, or nickel? by weight of alumina.

tungsten sulfide.

In reaction zone 16 the distillatefraction and hydro gen are passed over the catalyst at such a rate that the amount of said distillate fraction is within the range of A to 3 volumes per volume of catalyst per" hour. I It is preferred to have a reaction pressure Within the range of 700 to 800 pounds per squareinch and a temperature of reaction within the range-of 575 to and, more preferably; within the range of It will sometimes be fountl 750 F. about 650 to 750 F. preferable to conduct the operation within the temperature range of 625 to 675 F.

From reaction Zone 16 a liquid product containing dissolved gas and a small amount of low flash point liquid is removed through line 17 and passed to a sepa rator-stripper vessel 18'Where the dissolved gas is separated from the liquid fraction and is removed through outlet line 19. A low flash point lighter-than-lube liquid fraction is also stripped from the hydrogenated lubricating oil fraction and removed through outlet 20. The gasfr eeflash-corrected liquid fraction is removed from separator 13 through line 21 and passed to a solvent extrac-- tion zone. 22l where. it --is separated into a ralfinate frac-- tion which is removed through outlet line 23 as the desired high quality lubricating oil fraction and an extract:

dioxide,fur-fural, etc. may be employed in accordance with conventionaltechniques in the solvent extraction zone-22 to provide' the lubricating oil rafiiate fraction 23.. Plienolfis a preferred selective solvent which is employed with particularly desirable results in a manner well known to those .skilled in the art. By way of example, i

when the extraction step is conducted utilizing phenol as the selective solvent, such extraction step may be carried outata tempcraturewithin the range of to 250 Patented Dec. 23, 1958.,

F. Liquefied sulfur dioxide may be used as a selective solvent, in which case the extraction step may be carried out at a temperature within the range of about 30 to 120 F. As a further example, when furfural is employed, the extraction step may be carried out at a tem' perature within the range of about 150 to about 300 F.

A flow sheet for the treatment of a lubricating oil fraction derived from 21 Mid-Continent type crude is shown in Fig. 2. In Fig. 2 a Mid-Continent type oil fraction is withdrawn from stock tank 31 by line 32 and passed through furnace 33. The heated oil is withdrawn through line 34 and hydrogen is added thereto from hydrogen inlet line 35, and the oil and hydrogen then pass to catalytic reaction zone 36. Liquid product with dissolved gas and a small amount of low flash point liquid is withdrawn from catalytic zone 36 by means of line 37. 1

The liquid fraction containing dissolved gas is passed from line 37 to separator-stripper 38 where the gas is separated and removed through outlet line 39, the low flash point liquid through line 40 and the liquid phase free from gas and low flash point liquid is withdrawn through outlet line 41. The steps carried out in units 31 through 41 may be identical to the corresponding steps carried out in units 11 through 21 of Fig. 1 and in order to simplify the description, these conditions will not be specifically set out with regard to Fig. 2. However, in Fig. 2 the fraction withdrawn through line 41 contains an appreciable amount of wax and it is desirable to remove said wax prior to the solvent extraction step. For this reason the fraction in line 41 is passed to a de waxing step 42 where it is separated into a wax fraction removed through line 43 and the dewaxed lubricating oil fraction which is removed through line 44. The de- Waxing of waxy lubricating oils is conventional to the art. Any of the conventional means for dewaxing the 'oil, as by the use of solvents, may be employed. The dewaxed oil fromline 44 is passed to a suitable solvent extraction zone 45 where it is separated into a raflinate fraction removed through outlet line 46 as the desired lubricating oil fraction and an extract fraction which is removed through outlet line 47. To realize the full advantage of this invention, it dewaxing is required, the dewaxing step must be carried out subsequent to the hydrogejnation step. The sequence of operations after the hydrogenation step is not critical and may be selected to be most convenient to the operator. For example, the dewaxing step may precede or follow the solvent extraction step,

4 The advantages of the present invention will be further seen by reference to the following examples:

EXAMPLE I Samples of lubricating oil distillates derived from Mid- Continent type crude known as Panhandle light motor oil were used as the charge stocks. The specifications for these oils are as follows:

Gravity, API 29 minimum. Flash, F 450 minimum. Viscosity at 210, SSU 54-58.

Viscosity index 102 minimum. Pour point, F 15 maximum.

A sample of this distillate oil known as Sample A and another sample known as Sample B were subjected to hydrofining conditions as follows:

The flash-corrected lubricating oil products from the hydrofining of Table I were dewaxed at a temperature in the range of -5 to 10 F. using a 5/ 1 ratio of secondary butyl acetate solvent/oil.

Samples were then extracted with phenol. In carrying out this extraction, another sample, sample C, which had not been subjected to hydrofining, but which had been clay contacted at 400 F. for 30 minutes, was divided into three portions with one portion inspected as reported in column 7 and the other two portions phenol extracted and inspected as reported in columns 8 and 9 of the following Table II. The product resulting from the treatment of sample A of Table II was divided into three fractions with one fraction inspected as column 1 and the other fraction solvent extracted as columns 2 and 3 in the following Table II. The product resulting from the treatment of sample B of Table I was divided into three portions with one portion inspected as reported in column-4 and the other two portions phenol extracted and inspected as reported in columns 5 and 6 of the following Table H.

Table 11 Sample A Sample B Sample 0 Columns 2 3 4 5 6 7 8 9 Extraction Conditions:

Vol. percent phenol treat 187 124 108 200 Inspections:

Reflinate or dewaxed feed- Feed Feed Feed Dark Color, Tag Robinson- 2% 9% 10 2% 10 10% 36 9% 1e Extraction Yield, Vol.

Percent Based on Feed 79. 2 74. 5 8L 7 78. 4 79. 0 70. 2

The advantage of hydrofining prior to solvent extraction is-shown in Fig. 3 in which the yields reported in Table II are plotted in the form of a curve. By way of a simple example which may be derived from the curve of Fig. 3, if it be assumed that a 150 volume percent of phenol feed is used the volume percent rafiinate yield without the preliminary hydrofining step is approximately 74% whereas with mild hydrofining the volume percent rafifinate yield is increased to 78% and with severe hydrofining the yield is increased to approximately 81%.

EXAMPLE 2 A lubricating oil distillate fraction derived from Coastal distillate having a viscosity of 100 SSU at 210 F. was used as the feed stock. This feed stock was divided into three fractions one of which was subjected to hydrofining with one Volume of feed per volume of catalyst per hour at 700 F. temperature, a pressure of 750 pounds per square inch gauge and 1400 standard cubic feed of hydrogen per barrel of feed stock. The product from this hydrofining step was then subjected to phenol extraction as reported in column 2 in Table III, hereafter, while another sample which had not been hydrofined was subjected to phenol extraction as reported in column 1 in Table III hereafter. The third sample was subjected to no treatment and inspections of this sample are reported in column 3 of Table III hereafter:

Table III Column 1 2 3 Treatment Phenol Extraction Hydrothen Phenol Extracted Feed Extract Vis./210, SSU Gr., API Yields (based on feed) Extraction. Vol. Percent Overall, Vol. Percent 1 1 96% yield in clay contacting step. 1 98.0% yield in hydrofining step.

It will be seen that an overall yield of about 85% is obtained when following the procedure of the present invention of hydrofining and then phenol extraction as compared with an overall yield of about 78% when no hydrofining step is used.

EXAMPLE 3 A lubricating oil fraction derived from a Coastal type crude oil and having 1000 SSU viscosity at 100 F. was used as the charge stock. This stock was divided into three fractions. The first was not treated but was inspected with the inspections reported in column 3 of Table IV hereafter. The second sample was phenol extracted with the conditions of phenol extraction and the inspections of the product reported in column 1 of Table IV hereafter, while the third fraction was treated in accordance with the present invention by hydrofining at a temperature of 700 F., pressure of 750 pounds per square inch, liquid space velocity of .5 v./v./hr. and an inlet hydrogen rate of 1000 standard cubic feet per barrel of feed, the product from this reaction having gas and low flash point liquid separated therefrom and then phenol extracted with the conditions of phenol extraction and in- 6 spections of the product from the phenol extractiori'step reported in column 2 of Table IV hereafter:

Table IV Charge Stock 1000 CD Column 1 2 3 Hydro Phenol fined Treatment Extracted then Feedv Phenol Extracted Extraction Conditions:

Treat, vol. Percent 168 168 Temperature, F.-

Tower .top 170 170 Tower bottom 160 160 Percent H5O injection 2 2 Percent H2O in phenol 4 4 Inspections:

Stripped Rafiinate Gravity, API 25. 9 26.0 21. 3 Vis./100, SSU 516 502 1043 Vis./210, SSU 58. 6 58.1 69. 7 is. Index 64. 8 65. 4 22 Stripped Extract Gravity, API l2. 9 14.1 Vis./210, SSU on. o Yields, Vol. Percent (based on feed)- Extraction .Q 66.6 76. 2 Overall 66. 6 71. 6

It will be seen from results reported in Table IV that the practice of the present invention resulted in an overall yield of 71.6 whereas the overall yield obtained when the sample was phenol extracted was only 66.6.

One skilled in the art of preparing lubricating oils will appreciate the substantial advantage in the higher yields obtained by the practice of the present invention.

While specific examples have been given, it will be understood that said examples are given by way of illustration only and not by way of limitation.

We claim:

1. An improved process for treating a lubricating oil distillate fraction derived from a crude oil taken from the group consisting of Mid-Continent and Coastal type crude oils comprising the steps of hydrogenating said lubricating oil distillate fraction over a hydrogenation catalyst in the presence of hydrogen in an amount in the range of from 200 to 2000 cubic feet per barrel of said oil distillate while passing the hydrogen and said fraction co-currently over said catalyst at a rate within the range of A to 3 volumes of said fraction per volume of catalyst per hour at a pressure in the range of 700 to 800 pounds per square inch and at a temperature within the range of 650 to 750 F. to form a liquid phase containing hydrogen light hydrocarbon and a small amount of low flash point liquid, subsequently separating the gas and low flash point liquid from said liquid phase to form a gas-free, flash-corrected liquid lubricating oil phase, contacting at least a portion of the lubricating oil components of said liquid lubricating oil phase with phenol in a solvent extraction zone to form an extract phase and a rafiinate phase and recovering the raflinate phase as product.

2. A process in accordance with claim 1 in which the lubricating oil distillate fraction is derived from a Mid- Continent type crude oil and in which gas-free, flashcorrected liquid lubricating oil phase is dewaxed to form a dewaxed oil fraction and said dewaxed oil fraction is the material contacted with phenol in the solvent extraction zone.

3. A process in accordance with claim 1 in which the lubricating oil distillate fraction is derived from a Coastal type crude.

4. An improved process for treating a lubricating oil distillate fraction derived from a crude oil taken from the group consisting of Mid-Continent and Coastal type crude oils comprising the steps of hydrogenating said lubricating oil distillate fraction over a hydrogenation catalyst having approximately 15% by weight of cobalt molybdate and 85% by weight of aluminum in the presence of hydrogen in an amount in the range of from 200 to 2000 cubic feet per barrel of said oil distillate while passing the hydrogen and said fraction co-currently over said catalyst at a rate Within the range of A to 3 volumes of said fraction per volume of catalyst per hour at a pressure in the range of 700 to 800 pounds per square inch and at a temperature within the range of 650 to 750 F. to form a liquid phase containing hydrogen, light hydrocarbon and a small amount of low flash point liquid, subsequently separating the gas and low flash point liquid from said liquid phase to form a gas-free, flash-corrected liquid lubricating oil phase, contacting at least a portion of the lubricating oil components of said liquid lubricating oil phase with phenol in a solvent extraction zone to form an extract phase and a ratfinate phase and recovering the raflinate phase as product.

5. A process in accordance with claim 4 in which the lubricating oil distillate fraction is derived from a Mid- Continent type crude oil and in which said gas-free,

flash-corrected liquid lubricating oil phase is dewaxed to obtain a dewaxed oil fraction and said dewaxed oil fraction is contacted with phenol in the solvent extraction zone.

6. A process in accordance with claim 4 in which the lubricating oil distillate fraction is derived from a Coastal type crude.

7. An improved process for treating a lubricating oil distillate fraction derived from a crude oil taken from the group consisting of Mid-Continent and Coastal type crude oils comprising the steps of hydrogenating said lubricating oil distillate fraction over a hydrogenation catalyst in the presence of hydrogen in an amount in the range of from 200 to 2000 cubic feet per barrel of said oil distillate while passing the hydrogen and said fraction co-currently over said catalyst at a rate within the range of A to 3 volumes of said fraction per volume of catalyst per hour at a pressure in the range of 700 to 800 pounds per square inch and at a temperature within the range of 575 to 750 F. to form a liquid phase containing hydrogen light hydrocarbon and a small amount of low flash point liquid, subsequently separating the gas and low flash point liquid from said liquid phase to form a gas-free, flash-corrected liquid lubricating oil phase, contacting at least a portion of the lubricating oil components of said liquid lubricating oil phase with a selective solvent under solvent extraction conditions in a solvent extraction zone to form an extract phase and a ratfinate phase and recovering the raffinate phase as product.

8. A process in accordance with claim 7 wherein the selective solvent is phenol.

References Cited in the file of this patent UNITED STATES PATENTS 2,660,552 Blanding Nov. 24, 1953 2,687,982 Baumann Aug. 31, 1954 2,701,783 Long et a1. Feb. 8, 1955 2,734,019 Miller ct al. Feb. 7, 1956 

1. AN IMPROVED PROCESS FOR TREATING A LUBRICATING OIL DISTILLATE FRACTION DERIVED FROM A CRUDE OIL TAKEN FROM THE GROUP CONSISTING OF MID-CONTINENT AND COASTAL TYPE CRUDE OILS COMPRISING THE STEPS OF HYDROGENATING SAID LUBRICATING OIL DISTILLATE FRACTION OVER A HYDROGENATION CATALYST IN THE PRESENCE OF HYDROGEN IN AN AMOUNT IN THE RANGE OF FROM 200 TO 2000 CUBIC FEET PER BARREL OF SAID OIL DISTILLATE WHILE PASSING THE HYDROGEN AND SAID FRACTION CO-CURRENTLY OVER SAID CATALYST AT A RATE WITHIN THE RANGE OF 1/4 TO 3 VOLUMES OF SAID FRACTION PER VOLUME OF CATALYST PER HOUR AT A PRESSURE IN THE RANGE OF 700 TO 800 POUNDS PER SQUARE INCH AND A T A TEMPERATURE WITHIN THE RANGE OF 650 TO 750*F. TO FORM A LIQUID PHASE CONTAINING HYDROGEN LIGHT HYDROCARBON AND A SMALL AMOUNT OF LOW FLASH POINT LIQUID, SUBSEQUENTLY SEPARATING THE GAS AND LOW FLASH POINT LIQUID FROM SAID LIQUID PHASE TO FORM A GAS-FREE, FLASH-CORRECT LIQUID LUBRICATING OIL PHASE, CONTACTING AT LEAST A PORTION OF THE LUBRICATING OIL COMPONENTS OF SAID LIQUID LUBRICATING OIL PHASE WITH PHENOL IN A SOLVENT EXTRACTION ZONE TO FORM AN EXTRACT PHASE AND A RAFFINATE PHASE AND RECOVERING THE RAFFINATE PHASE AS PRODUCT. 